EFFECT OF LUBRICATION CONDITION ON RECRYSTALLIZATION TEXTURE OF ULTRA-LOW C-SHEET-STEEL HOT-ROLLED IN FERRITE REGION

The application of the EBSD technique with an SEM provides a new appro ach to the analysis of variations of the recrystallization texture in the thickness direction of ultra-low carbon sheet steels rolled in the ferrite region. A nonuniform recrystallization texture through the th ickness is formed due to the additional shear strain introduced by fri ctional force between the rolls and the material in sheet steel rolled with a friction coefficient over 0.15, [110]//ND recrystallized grain s being formed near the surface, and [111]//ND and [100]//ND recrystal lized grains being formed at the mid plane. On the other hand, [110]// ND recrystallized grains are not formed preferentially near the surfac e, and [111]//ND and [100]//ND recrystallized grains are formed unifor mly throughout the thickness in sheet steel rolled with a friction coe fficient under 0.15. Orientation imaging also reveals differences rela ted to the tolerance of [110]//ND recrystallized grains around the [11 0]//ND axis in sheet steel rolled without lubrication, in that [110]// ND grains with a small tolerance form at the 1/10 plane from the surfa ce and [110]//ND grains with larger tolerances form at thickness locat ions from the 1/10 plane toward the surface and center. The r-value de pends on the friction coefficient and increases significantly as the f riction coefficient decreases under 0.15, resulting in high r-values o ver 1.2. This change in the r-value with the friction coefficient corr esponds to the distribution of the recrystallization texture through t he thickness. Orientation imaging allows a more visual and intuitive u nderstanding of the nonuniformity of the recrystallization texture tha n conventional methods such as optical microscopy and X-ray diffractio n measurement.